This fujctions that this value will now Metatradsr assigned to variable C. Further calculations in the program, if any, can be performed with the variables declared within the calling function. In our case, the calling function is special start function, which contains the line for calling the user-defined function, whereas the variables declared within the calling function are A, B, and C. Thus, in the function, the calculations are performed using formal parameters, which allows us to create functions using arbitrary names of variables, irrespective of the names of values actually used in the program. We should note that the entire code of the program is located inside the special start function.
At this training phase, we will not pay special attention to this. Special functions and their properties are considered in detail in Special functions. Let us follow the execution of the program starting with the assignment operator. The right part of the assignment operator contains the specified constant; its value is three.
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The value of three the value of the right part is assigned to variable A located to the left of the equality sign in the assignment operator. The control is given to the next line. The right part of the assignment funchions contains the specified constant; laguage value is four. The value of four is assigned to variable B. The program goes to execution of the next line. This execution starts with the calculation of the right part of the assignment operator. The result of the calculations is the value of The details of how a program refers to variables to take their values are considered in Constants and variables. The next line represents an assignment operator, the right part of which contains a call for the standard function.
For this purpose, it executes calculations to the right of the equality sign first. The program calls for execution of the standard function MathSqrtwhich calculates square roots. Note that there is no description of this standard function anywhere in the program.
Metahrader descriptions of standard functions fujctions not be located in programs. In the text of a program, you can easily distinguish Metatradder standard function call by its appearance; they are highlighted in MetaEditor with dark blue by default, but funcctions may choose Mefatrader different color. The calculations are made in the standard function MathSqrt. The standard function MathSqrt has completed its calculations. It returns the obtained value, five the square root of The value returned by the function is now the content of the record. After these calculations have been completed, the thing takes a value.
The value returned by the function can be assigned to another variable or considered somehow in any other calculation. In this case, our value is the value of the right part of the assignment operator. On continuing execution of the assignment operator, the program will assign the value of five to variable C. The next line contains an operator that calls the standard Alert function. In this case, the function has taken two values as the passed parameters: It was noted above that not all functions must return a value. As a result of execution of the standard Alert function, a window will appear on the screen with the following line: The last operator in this program completes the work of the special start function.
A question may arise: The answer to this question is obvious: The properties of a user-defined function are specified in its description.
Whether a user-defined function returns a value or not depends on its algorithm; you decide while writing the program code of the function. A certain part of Metatrarer code that could previously be found in the special start function is unavailable now. It is replaced with the call for the user-defined function. However, the special start function is followed by the description of the user-defined function. The first two lines, in which integer variables A and B take numeric values, remain the same. Consequently, nothing changes in their execution. Its right part contains the call for the user-defined function. On executing this operator, the program will first call the user-defined function.
Note that the description of the user-defined function must be present in your program and placed immediately after the brace that closes the special start function that is, outside the special function.
In referring to the user-defined function, the program will Megatrader the esay steps. Calling for variable Functioms in order to get its value in our funnctions, three 6. Calling for variable Metatrader easy language functions in order to get its value in our case, four Note that as soon as the program starts to call the user-defined function the function is user-defined, in our specific case, but this rule applies to all functionsthe program gets just a copy of the values of variables used as passed parameters, whereas the values of these variables themselves in this case, A and B are not supposed to change due to application of the user-defined function, nor do they really change.
The control is passed to the user-defined function. During the whole time of execution of the user-defined function no matter how long it takesthe values of variables in the calling program will not get lost, but will be stored. The first line in the description of the user-defined function is its header. The value of three the first value in the list of passed parameters is assigned to variable a the first variable in the list of formal parameters. The value of four the second value in the list of passed parameters is assigned to variable b the second variable in the list of formal parameters. Then the control is passed to the function body for it to execute its algorithm.
The first operator in the function body is the following line. The next operator is the following line of code. Here we find the square root of the value of variable c2. The order of operations is the same as in the previous example. The description of the standard function is not used either. The execution of the assignment operator results in assigning the value of five to variable c. In the next line, we have the following operator. In our case, it is the value of variable c, five. At this point, the execution of the user-defined function is over, the control is given back to the call site.
Recall that the user-defined function is called from the following operator.
Gipo A,B On completing the execution of the assignment operator, the program assigns the value of five to the variable C. The next operator is executed in the same way as in the previous example. The last operator in this program completes the work of the special start function, and it simultaneously completes the work of the entire program. The MQL Language: Developed by MetaQuotes Software Corp.
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Scripts are Metatarder when traders want a single execution in an action. They are only acceptable for the start of an event and cannot process cunctions other trade actions. This is a set of custom functions that is intended to store and distribute the same used parts of the program. MetaTrader 4 vs MetaTrader 5 The relatively recently launched MetaTrader5, is not that much different from its prototype MT4, even though it is advertised as substantially more advanced.